Placental Function Flashcards
What are the functions of the placenta?
To replace functions of adult – delivery of gases & nutrients, excretion of waste products, storage of energy, placental derived hormones, protect against toxic substances & the maternal immune system
How does the placenta efficiency stay high enough to match fetal growth?
Exponential increase in cotyledonary microvascular density & partly mediated by increased uterine and umbilical blood flow
What factors influence the passive diffusion of substances?
Blood flow, structure, morphology, electrical gradient & concentration gradient
Why is the change in paO2 much higher in the fetus?
Cardiovascular output is much higher, meaning partial pressure is not essential
Which type of haemoglobin has a much higher affinity for oxygen?
Fetal haemoglobin, compared to adult haemoglobin
With regards to nutrient exchange, rank the placentations in order of efficiency?
Epitheliochorial (least), endotheliochorial, haemochorial (most)
How does the fetus increase maternal glucose transfer in late gestation?
Fetus will increase O2 consumption to drive increased gradient
What is nutrient exchange determined by?
Passive mechanisms & the density and activity of carrier molecules for AAs and glucose
What are the three stages of amino acids transfer?
Uptake, transport into trophoblast, release into fetal circulation
What is IUGR?
Intra-uterine growth retardation – impaired growth and development of the mammalian embryo/fetus or its organs during pregnancy
What is the primary isoform for transporting glucose?
GLUT-1
In freemartinism, how does sharing of the circulation occur?
Through anastomoses, which may be arterio-venous, arterio-arterial or veno-venous
What are the common causes of IUGR?
Nutrient imbalance, intestinal malabsorption, ingestion of toxic substances, stress, disturbances in metabolic and homeostatic mechanisms, dysfunction of the uterus endometrium or placenta, poor management
What factors impair placental efficiency?
Placental size/weight, uteroplacental blood flow, Interdigitation of the placenta with maternal endometrium – surface area
What is gynaecological immaturity?
Breeding animals at immature body weight, mother and fetus compete for nutrients
